Ice dam risk in Monroe, WI
Will your roof get ice dams in Monroe, WI?
24.4 dam days a winter
High risk. On an ordinary house in Monroe, conditions for an ice dam come on about 24.4 days in a normal winter, mostly in January and February.
Monroe averages 42 inches of snow a year and about 70 days with snow on the ground. Snow that lies that long is what turns a little attic heat into a ridge of ice at the eave. The conditions that make a dam need all three at once: snow, cold at the eave and heat above it.
What your attic does to that number in Monroe
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 11.1 | Moderate |
| Typical, some insulation, not air-sealed | 24.4 | High |
| Older or poorly insulated, warm attic | 41.1 | Severe |
Sealing and insulating a typical attic takes out about 13.3 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 41.1 days.
What to do about ice dams in Monroe
- Air-seal the attic floor: the gaps around the hatch, light fixtures, plumbing stacks and the top plates of interior walls. This is the fix that removes the cause, and it usually costs less than a season of contractor ice removal.
- Rake the bottom three or four feet of roof after any storm that leaves more than about six inches, from the ground with a roof rake.
- At the next reroof, ask for ice-and-water membrane under the shingles from the eave to at least 24 inches inside the wall line. It does not stop a dam; it stops the leak when one forms.
Which to spend on first: air sealing or heat cable.
Monroe winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 11.8 | 22.5 | 9.0 |
| February | 10.5 | 20.2 | 7.5 |
| March | 4.7 | 9.0 | 2.1 |
| April | 1.4 | 0.7 | 0.1 |
| May | 0.3 | 0.0 | 0.0 |
| October | 0.4 | 0.1 | 0.0 |
| November | 1.8 | 2.4 | 0.5 |
| December | 10.6 | 15.4 | 5.3 |
Monroe next to nearby towns
Monroe ranks 57 of 98 Wisconsin cities here for ice-dam days, behind Wausau at 41.6 days.
- Freeport, IL 22 mi, 19.2 days
- Oregon, WI 26 mi, 23.9 days
- Verona, WI 27 mi, 22.2 days
- Fitchburg, WI 29 mi, 22.2 days
- Stoughton, WI 31 mi, 23.9 days
Where these numbers come from
NOAA 1991–2020 climate normals from Monroe Wwtp, 1.6 miles from Monroe. A dam day is a day with snow on the roof and freezing at the eave while heat or sun melts the snow above it. This describes a normal winter, not this one.